Work is proposed on a series of projects designed to provide information on the molecular events that occur during the multiplication of Reovirus, Vaccinia Virus and RNA Tumor Viruses. Among these projects are investigations of the nature of the enzymes present in reovirus cores, of reovirus morphogenesis, of the function of reovirus-coded proteins and of the genetic relatedness of reovirus serotypes 1, 2, and 3; studies of the mode of synthesis and function of poly(A) sequences at the 3'-ends of messenger RNAs and studies of the transcription of vaccinia virus DNA both in vitro by viral cores and in vivo during defined stages of the viral multiplication cycle, including an investigation of the nature of the viral proteins synthesized during these stages; and studies on the function of three phosphoproteins present in avian retrovirus particles in their phosphorylated and dephosphorylated states. It is also proposed to develop techniques for cloning the mouse interferon gene.